Load compensating brake



Oct. 5, 1948. A, ,1 BENT LOAD COMPENSATING BRAKE 5 Sheets-Sheet 1 Filed Jan. 51, 1946 INI/ENTOR ARTHUR J. BEN T mmf E m. I/m 1|\ .r vm.

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m LQ o Oct. 5, 1948. v A, J, BENT 2,450,464

LOAD COMPENSATING BRAKE ATTORNEY Oct. l5, 1948. I A. J. BENT 2,450,464

LOAD COMPENSATING BRAKE Filed Jan. 31, 1946' 3 Sheets-Sheet 3 MI5- 1 l I INVENTOR BY Amm-JR 1J. BENT A TTORN E Y Patented Oct. 5, `1948 Arthur .L Bent, Penn Township, Allegheny County, Pa., assigner to The Westinghouse Air Brake Company, Wilmerd'ing'-, Pa., a corporal tion of Pennsylvania Application January 31, 1946-, SerialNo. 644,446

v 44 Claims.

1 This invention relates to load compensating or variable load brake equipment for vehicles, and

more particularly to that type of equipment-which is constructed and arranged to be automatically adjusted or conditioned to Vary the braking force according to the position that the vehicle body, under various loads, assumes relative to a vertically ixed part of a truck.

The present trend toward the use of light weight materials in the construction of railway freight cars has resulted in much higher ratios of gross weight to tare weight than ever before encountered. Since the braking force in relation to the weight of an empty car must be such as to avoid wheel sliding and excessive train shock, the braking force on lighter weight cars will consequently have to be lower than heretofore. Because the gross weight is limited only by theV load limit for the'trucks, which remain unchanged, the lower braking force will be inadequate for proper control of such cars when loaded.

The principal object of this invention, therefore, is to provide a variable load brake equipment which will operate in conjunction with the present type of fluid pressure brake equipment so that the braking force will. be suiiiciently loW on an empty car to prevent wheel sliding and will be increased in relation to any increase in the gross weight of the car so thaty a loaded or partially loaded car may be properly controlled in a train.

Another object is to provide a variable load brake equipment which will require only a single standard auxiliary reservoir and only a single brakecylinder, and which will operate in conjunction with the other parts of the standard fluid pressure freight brake equipment to obtain substantially the present application and release time intervals on a car without altering the flow capacities of any passages in such other parts.

Sti-ll another object is toy provide a variable loa-dbrake equipment of the type employing a single brake cylinder in which the effectiveness of the fluid pressure may be varied, the eiective pressure for any given application being proportioned according to the weight of the load carried by the vehicle. f

A further object is to provide a variable load brake equipment employing a single brake cylinder, which brake cylinder will have. substantially the same' displacement volume as the standard freight brake cylinder.

A stillI further object is to provide a Variable load brake equipment which employs a single brake cylinder and which will providein the 2'. brake cylinder substantially the sam-e fluid pressurev curve chiara-cteristicsz as in the standard brake cylinder regardless of the loading on the vehicle.

To attain these objects the variable load brake mechanism embodying this invention employs a single brakecylinder device, which preferably has a larger diameter and a shorter pistonl travel than the standard device. The lower degree` of braking force which is necessary ior vehiclesV carrying lighter loads is obtained by the use oi a relay valve mechanism which includes two opposed diaphragms having operatively coupled thereto a self-lapping valve arrangement. Onediaphragm is arranged to operate the valveV arrangement, in response toy the pressure of flu-id being supplied to one side of' a brake cylinder piston in the usual manner, to supply this iiuid to they opposite side of the bra-kecylinder piston and to the other diaphragm until such opposing brake cylinder pressure4 actsv on: the other diaphragm to move the valve'arrangement to its lapped position. By'reason. of the shape of the follower for the; first mentioned diaphragm the degree `or effectiveness; of

i said diaphragm decreases, and therefore the amount of fluidsupplied to the opposite side of the brake cylinder pis-ton decreases, as the diaphragm ispositioned further away from its follower. 'l'he diaphragm is positioned, according to the weight of the load carried, by a mechanism which is responsive to fluid under pressure supplied from the brake pipe while being charged below a certain degree of pressure to initially actuate a measuring element intoV engagement with a vertically iiXed' part relative toV a sprung part of the vehicle, and thereafter to displace the first mentioned diaphragm away from its follower a distance which. becomes greater as the weight off the lading becomes. greater. Thus the opposing ii-ui'dl pressure on the brake cylinder pis- A ton` decreases and the braking force increases as the shifftable diaphragm is displaced further away from its follower toward load position according tothe increase in the weight of the lading on the vehicle.

Other objects and advantages will become apparent in the following more detailed description of the invention taken in connection with the accompanying drawing wherein the Fig. 1 is a diagrammatic view partly in section of, a variable load brake equipment embodying the invention; Fig. 2 is an enlarged diagrammatic View in section of a portion of the variable load brake equipment shown i-n Fig. l, and Fig. 3 is; a view partly in section or a modi'cation of the equipment shown in Fig. 2.

DESCRIPTION As shown in the drawing, the variable load fluid pressure brake equipment may comprise the usual brake pipe indicated by the reference numeral I, a branch pipe 2, a brake controlling valve device 3, an auxiliary reservoir 4, an emergency reservoir 5, a cut-01T valve device 6, retaining valve device 1, a Variable load valve mechanism 8 and a brake cylinder device 9.

The brake controlling valve device 3 may be of substantially the same construction and have the same operating characteristics as the AB valve device fully described in the patent to Clyde C. Farmer, No. 2,031,213, issued February 18, 1936 and assigned to the assignee of the present invention, and in view of this it is deemed unnecessary to show and describe this device in detail. It will of course, be understood that this device operates upon a service reduction in brake pipe pressure to supply fluid under pressure to eiect a service application of the brakes, upon an emergency reduction in brake pipe pressure to effect an emergency application of the brakes, and upon an increase in brake pipe pressure to effect a release of the brakes 'and the charging of the brake equipment.

It is preferred for this invention that the variable load valve mechanism 8 be mounted by any suitable means to a sprung portion of a car, such as the under side of the car body, so that the deflection of the springs resulting from a change in the Weight of the lading on a car equipped with an apparatus embodying this invention may be measured and the mechanism conditioned according to this deflection. For this purpose a measuring element II) may be operably attached to one end of the wire portion of a Bowden wire I I, which Wire portion may be slidably mounted in the usual sheath or covering securely clamped to the car body I2, the wire portion being attached at its other end to a lever I3 by means of a pin I4, so

that the measuring element I may be actuated upwardly into engagement with a bottom surface I5 of a vertically stationary part such as a truck axle for example, or a horizontal bar attached to a spring plank or other part xed vertically relative to a sprung part.

eration of the variable load valve mechanism 8 acting through the medium of a pivotal pin I6,

a link I1 which is connected by means of a pin I8 to a link I 9, and through the lever I3 which is pivotally connected to the link I9 by means of a pin 20. The lever I3 is rockably mounted by means of a pin 2I on a sprung part of the car, preferably, the underside of the car body. A series of holes 22 are provided along the lever I3 for the reception of the pin I4 so that the leverage may be adjusted to correspond to the range of spring .deflection for any particular car,

The cut-off valve device 6 is provided for the purpose of controlling the supply of fluid under pressure from the brake pipe I to the variable load valve mechanism 8 for the operation of the Measuring movement of the element I0 may be effected through the opsmall piston 26, and a hollow stem 21 extending between and connecting both pistons. Dened by the pistons 25 and 26 together with the casing 23 is a chamber 28 which is in constant open communication by way of a passage and pipe 29 with a load measuring cylinder 38 in the variable load valve mechanism 8.

At the other side of the piston 25 there is a chamber 3I which is in constant open communication by way of a pipe and passage 32 with a brake pipe passage 33 provided in the brake controlling valve device 3, the passage 33 having a choke 34 therein. In the chamber 3| a valve 35 is mounted so as to operatively engage a tubular valve seat member 36. This valve seat member 36 is mounted in the casing 23 so as to extend from the chamber 3l through the piston 25 so as to establish, together with a port or ports 31 in the piston stem 21, a communication between chambers 3l and 28, which communication is controlled by the valve 35. Also contained in the chamber 3I is a spring 38 which biases the valve 35 toward its seated position. Resiliently secured in the piston member 24 by means of a spring 39 is a strut member 48 which extends through the tubular valve seat member 36 and normally holds the valve 35 in its unseated position in which it is shown in the drawing.

At the other side of the piston 26 is a chamber 4I which is constantly open to atmosphere by way of a passage 42. As will more fully appear later, communication may also be established between chamber 4I and the chamber 28 by way of a bore 43 through the piston 26, which bore is normally closed at its inner end by an exhaust valve 44. This valve 44 is carried within the piston 2B at the lower end of the spring 39, which spring biases said valve toward its seated position in which it is shown. Interposed between and operatively engaging the bottom wall 0f the casing 23 and the lower end of the piston member 24 is a spring 45 which constantly urges the piston member 24 toward the position in which it is shown. For unseating the valve 44 upon downward movement of the piston member v24 a stem 46 is mounted in the chamber 4I and extends axially through said chamber and a part of the bore 43 in the piston 26 toward the under side of the valve 44.

of a passage 5I in the casing 41. Interposed between the casing 41 and the piston 48 and operatively engaging the same is a spring 52 which tends, at all times, to move the piston toward the left-hand position in which it is shown. The piston 48 is provided with a stem 53, which stem extends through the chamber 50 and a suitable opening 54 in the casing 41 to make connection eXteriorly with the link I1 by means of an adjustable shank 55 and thepin I6.

The variable load valve mechanism 8 further comprises an adjusting mechanism 56 and a re- Alay Valve mechanism 51, the adjusting mechanism acting under the power and control of the load measuring cylinder 30 to condition the relay valve mechanism for operation according to the Weight of the lading on the car. The adjusting mechanism 56 comprises a casing 58 having slidably mounted therein .a `diaphragm-positioning'fbar 59 anda cam member-99 for controlling the'lockingfof Ythebar59. An operating z'lever 6| is rockably vmountedtolrthe casing 58fby means of af-pin 62 for operatively connecting the load measuringpistonAto the bar 59l andthe cam member 69; The lower end of the operating lever 6| Ymakes a jointed connection 'with the stem 53 of the piston 48 by means of the pin`-|9, link |1, pin IB andzadjustable shank 55. rIhe upper end of the lever 6| is -operatively Yconnected with the end of :the bar 59 by means of Va pivot pin B3 `and a link 64, which link has slidably mounted in a slot therein a pin 66 at the upper end of a lever61, the lever 91 -being rockably mounted on afpin. 68 carried by the casing 58'and -joined lat its -lower end to the bar 59 by means o f a pin .69. Intermediate the pins |8 and 92, the operating lever 6| is operatively connected with the cam member 9|) by means of a pin 19, link 1| and pin 12.

The positioningbar 59 is held in -itsadjusted position by means Aof a pawl 13 under a dog14 rockably mounted on their respective pins 15 and 16 carried by the casing 58. The pawll 13 and-dog 14 `are pressed by torsion springs 11 and 18, respectively, so as to rock .the pawl into locking engagement with a toothed portion 19-of the bar 59 and rock the dog 14 against the pawl 13 to hold the pawl inV its locking position. cam ymember 69 'is provided with an linclined surface 89 which is effective through the medium of a strut 8| to Vrotate the dog 14 out ofengagement with the pawl 13 vwhen the cam member is shifted outwardly. An inverted V-shaped projection 82 on the cam memberl 99 may effect, through the medium of a spring-pressed ball 83 and a strut 84, the disengagement of the pawl 13 in a similar manner. The cam member 991s further provided with an inclined surface 95 .f

which effects through the medium of a strut 86,

v the movement of a spring biased check valvev 81 mounted in a chamber 88 formed in the casing 58 frorn its exhaust closing position to itssupply closing position.

As will later be pointed out, the relay valve mechanism 51 embodies a number of novel constructions and control characteristics. This mechanism comprises .a casing 89 having formed therein a cylindrical bore 99- in which is slidably mounted an annular diaphragm carrying member 9| which is rigidly attached to -one .end of the diaphragm positioning bar 59 for movement thereby. Interposedbetween the casing 58 and the member 9| is a spring 92 which constantly urges the `member to the left toward empty position in which it is shown. Tightly clamped about its periphery between two parts of the member 9| is a flexible diaphragm 93 which with .the member .9| defines a pressure chamber 94. This chamber 94 is Yin constant open communication with. the valve chamber 88Ybyway of a passage 95 and a tube 99, the tube being arranged to move with the member 9| and telescope within Aa passage 91 formed in the casing v59.

At the other side of the diaphragm 93.15 a chamber 99 which is always open to atmosphere by way of va passage 99. Spaced from the diaphragm 93 and serving therewith to define the chamber 98 is a flexible diaphragm |99 `rigidly clamped about its periphery between two yparts of the casing 89. On the other side of the diaphragm |99 there is a valve chamber |9| which is 'in constant open communication by way of 'a passage' |92 Awith the "bra-ke `cylinder Adevice 9.

The n Contained in the chamber 98 and slidably mountedina bore |93 in the `casing 89' isa :thrust member |94 having mounted at one end a movable abutment or follower member |95which may operatively engage a portion of the diaphragm 93. A surface |96 lof the ymovable-,abutment l 95isin the form generally of aparaboloid. As the member 9| ismoved to theright away from the member |95 the surface |96 will engage less and less of the diaphragm 93 until in the extreme right-hand position, which is load position, it will just :engage in'tangential relationship the adjacent surface of the diaphragm 93. As will bev apparent subsequently, the exact curvatureofthe surface |99 will depend upon theY desired relationship Ybetween the degree of braking force ydesired to the weight of the lading on the car. If a straight-.line relationship is desired it will bevfoundfrom experiment that surface |96 should conform substantially in curvature to a parabola, as viewed .in Fig. 2.

Mounted on Vthe other end of the thrust member |94 is a follower member |91 having a bore and passage |98 therein which at its inner end is open to the chamber 98 and at its `outerend leads to the chamber |9l. The outer end of the bore and passage Y99.15 encircled by a valve-seat |99 which is normally engaged by an exhaust valve ||9 mounted ina Ysupport member |||,in the chamber I9! and secured to the .casing 89. A strut ||2 engages the outer side of the valve H9 yand extends through asuitable opening in the support member to engage the inner surface of a supply valve |l3. This supply valve HS, in response tothe pressure of a spring H4, operatively mounted in a chamber l5, normally closes a passage H9 leading from the chamber i'i to the chamber H5. The chamber H5 is in constant open communication with the valve chamber 89 by way of a passage ||1 and with Ythe brake cylinder 9 by way of an additional passage ||3 leading from .passage Ill.

Referring now to Fig. 1, it will readily be seen that the brake cylinder device 9 is not of thc conventional .type having a pressure chamber at one side of a piston and a non-pressure, or atmospheric chamber at the other side of the piston. The brake cylinder device 9 is provided with a cylinder casing ||9 and a piston |29 having at one side a chamber |2i which is open to the chamber ||5 in the relay valve device 51 by way of passages H8 and ||1 and to the brake controlling valve device 3 by Way of a pipe |22. At the other side of the piston |29 is a chamber |23 which is open to the chamber |9| in the relay valve vdevice 51 by way of the passage |92. The piston |29 is provided with a hollow stem |24 which is arranged to extend through the chamber G29 and av suitable opening |25 in the casing H9. At this opening, however, the casing ||9 is provided witha pair of sealing rings |29 which slidably engage the casing H9 and the hollow stem 24 so that fluid pressure may bey established in the chamber |23, which chamber is defined by the piston |29, the walls or the casing H9 and the hollow stem |24. Contained in the chamber |23 and encircling the stem |24 is a release spring A| 21 forreturning the piston |29 to release position when the fluid under pressure in the brake cylinder chamber |2| and pipe |22.is released.

The piston |29 isvof 'such .diameter that it can provide, under normal operating pressures, suihcient force to brake a fully loaded car, which diameter might be 1 2 inches. When lighter loads are carried in-the car, the'variable load 'valve mechanism 8 operates to supply iiuid under pressure to the chamber |23. It will be noted, however, that the back pressure thus created is effec tive only over that area of the piston which will serve to define the chamber |23. Since it is preferred to keep this area small, the piston stem |24 Will have a relatively larger diameter, such as seven (7) inches for example, than that of the usual brake cylinder piston stem.

OPERATION Initial charging of the equipment Assuming the vehicle embodying the invention to be empty and separated from a train, the brakes on the vehicle released, the brake pipe I of the vehicle depleted of iiuid under pressure and the diaphragm 93 of the variable load valve mechanism 3 temporarily disposed in the empty position in which it is shown, the brake controlling valve device 3 will be in brake applied position and the several other parts of the equipment will be in the positions in which they are shown.

Now if the empty vehicle is placed on a train, the brake pipe I will of course be connected at each end of the vehicle to the corresponding brake pipe at the adjacent end oi each adjacent vehicle of the train and as a result the brake equipment is in condition to be charged with uid under pressure in the usual manner. In initially charging the equipment, fluid under pressure supplied in the usual manner to the brake pipe I flows through the branch pipe 2 to the chambers at the faces of the service and emergency pistons of the brake controllingvalve device 3, moving the pistons in due course to their brake release and equipment charging position. Fluid under pressure will then flow to the several other chambers of the brake controlling valve device 3, and thence in the usual manner, to the auxiliary reservoir 4 by way of a pipe |28, and to the emergency reservoir 5 by way of a pipe |29. At the same time, iluid under pressure will also flow from the brake pipe I through branch pipe 2, passage 33 and the choke 34 therein, and connected pipe and passage 32 to chamber 3| in the cut-01T valve device B. From chamber 3| fluid under pressure ows through the tubular valve seat member 35 to chamber 28, and then-ce by way o1" connected passage and pipe 29 to chamber 4.9 of the load measuring cylinder 3|! in the variable load valve mechanism 8. In response to the pressure of iluid thus supplied to the chamber 4l?, piston 418 will move to the right against the opposing pressure of the spring 52, effecting, through the medium of the stem 53, shank 55, pin I6, link pin I8, link I9, and pin 20 the rocking of the lever I3 in a counter-clockwise direction about the pin 2 I. As the lever I3 is rocked in this manner it acts through the medium of the pin I4 and the Bowden wire I I to move the measuring element Il? upwardly into engagement with the bottom surface of a vertically stationary lpart of the vehicle. Movement of the piston 48 to the right acting through the medium of the shank 55, pin IS, link Il, pin I8, also effects the rocking in a counter-clockwise direction of the lever 6| about the pivot pin 62. As the lever El rocks in this manner it causes, through the medium of the pin 19, link 'II and pin 12, the outward movement, to the right as viewed in Fig. 2, of the cam member 60. As the member 6B moves outwardly, the surface 8U thereof will engage the adjacent end of the stem 8|, thereby propelling the stem 8| in an upward direction. Upward movement of the stem 8| will cause the dog 'I4 to rock against the force of the spring 'I8 in a clockwise direction about the pin 16 and away from the pawl '13, thus leaving the pawl free to .be rocked out of engagement with the bar 59. Further outward movement of the cam member 60 will cause the spring-pressed ball 83 to remain located under the strut 84 so that when the boss 82 passes under the ball 83, it will effect through the medium of the strut 84, the rocking of pawl 'I3 in a counter-clockwise direction about the pin 'I5 and against the force of the spring '11, and thus out of engagement for a period of time with the toothed portion 'I3 of the bar 59.

It will be noted that the pawl 'I3 serves as a detent against inward movement only of the bar 59. Consequently, with the bar located in its innermost or empty position in which it is shown in Fig. 2 there will be no reaction to the disengagement of the pawl i3 from the bar. If, however, the bar 59 had previously been locked in some position to the right of the position in which it is shown, disengagement of the pawl 'I3 would permit the spring 32 to return the diaphragm carrying member 9| to empty position. Thus, it will be seen that, during the charging of the brake pipe i from atmospheric pressure, the member 9| will automatically lbe returned to empty lposition before it is again positioned according to the weight of the lading on the vehicle. If by reason of an accident the bar should fail thereafter to position according to the weight of the lading, the equipment will be conditioned for braking an empty vehicle and overbraking of an empty or lightly loaded vehicle, whichY would cause serious damage, is automatically prevented.

By reason of the engagement of the inclined surface 35 of the cam member i with the adjacent end of the strut 86 outward mo-vement of the cam member will effect movement of valve 87 from its upper seated position in which it is shown to its lower seated position. For reasons which will appear more fully later, fluid under pressure in chamber 95., may then flow to atmosphere by way of tube 3B, passage 91, chamber 88 and a passage l. Seating of the valve 87 in its lower position will prevent any supply of fluid under pressure from the passage I Il to the chamber 9E.

Rotation of the lever 3| in a counter-clockwise direction also causes movement of the link 64 toward the left handas viewed in Fig. 2, moving the right-hand end of the slot therein toward engagement with the pin 66. With the vehicle empty, however, the movement of the piston 43 in an outwardly direction, and consequently rocking of the lever 6I in a counter-clockwise direction, will be arrested by the engagement of the measuring element IE! with the surface I5 before the link 64 operatively engages the pin 66. The diaphragm carrying member 9| of the variable load valve mechanism 8 will therefore remain in the position in which it is illustrated, which is the position for braking an empty vehicle.

Now when the pressure of lluid in the chamber 28 of the cut-olf valve device 6 has increased to approximately 50 :pounds the pressure of iiuid acting on the piston 26 will be'suicient to overcome the opposing pressure of the spring A5 and the piston member 24 will be caused thereby to shift in a downward direction until an annular sealing rib I3 provided on the piston 25 engages a gasket |32 secured in `chamber 28 between two parts of the casing 23. Downward movement of the piston member 24 causes the strut member fl to move in a downward direction an-d thus permits-.the spring y3B-.to actuate the valve. 35.into sealing engagement with thetubular seat member 36Yto cutoff further iiow of iluidunder pressure from chamber 3| to chamber 28 by way of said member. Upon downward movement of the piston memberf24: the valve 44 is carried into engagement with the stem 46, so that the continued downward movement ofy theipiston 29 causesthe pistoniZ to move out of sealing engagement with theznow stationary valve` 44. Fluid under pressure in` chamber'49 ofthe load measuring cylinder 30 may nowflow to atmosphere by way of pipef29, chamber 28Y of the cut-0H valve device passages 3'! in the piston4 member 24, chamber 21 therein, bore 43 in the piston` 25, chamber 4I kand atmospheric passage 42.

When the pressure of fluid in chamber 49 of the load measuring cylinder 30 is slightly less thanthe opposing pressure of the spring 52, said spring will acti toshift the piston 48 to return the various associated parts to thel positions kin which theyare shown. Movement of the'piston48 to the left -vvill 4cause rocking of the levers (5| -andV I3 in aclockwise direction, thereby reversing the movement previously described and moving the measuring element I and the cam member 90 backftoy the positions in which they are shown.

It-Will be noted that, prior to the cut-01T operation of thefvalve device 6 previously described, the fluid at brake pipe pressure acted over the relativelysmalLareay of the piston 26- to oppose the upward force of the spring 45. Now, after the cut-off operation, the fluid at brake pipe pressure will act'over that portion of the piston 25` which is encircled/by the seatingl rib I3| to oppose the upwardly directedforce of the spring- 45. Since the effectivek area which-is exposed to brake pipe pressure is now much greater, it will be apparent that the'brakeA pipe` pressure will have to beY re- `ducedto `some 10W degreeV of pressure (such as Zpounds) before the spring 45 may prevail and return the piston and valve assemblage to the position in Awhich it is shownA inFig. 1.

Application of the brakeson an empty vehicle `When it is desired to effect an application of the brakes, the brake pipe pressure is reduced in the yusualma'nner, causing the brake controlling valve device 3 to function to supply fluid under pressure from the auxiliary reservoir 4 to the brake cylinder device 9 in order to advance the yusual brake shoes, not shown, into frictional engagement with the vehicle wheels. The flow of iluid under pressure from theauxiliary reservoir 4 to the brakecylinder deviceS is by way of the pipe |28, through the brake controlling valvevv device 3 and pipev |22 to the brake cylinder chamber I2I. Fluid under pressure may flow from chamber I2I by way of passages ||8 and II'I to chamber II'5 in the relay valve `device'51. Fluid underv pressure passage |I1 may also flow by way of valve chamber 88, passage S'Ltube 96, and passage 95 to the control chamber 94 in the relay valve device l.

When the pressure of fluid in the chamber 94 becomes-sufficient to .overcome the force of the spring I i4, the diaphragm 93 will act through the medium of the thrust member |04, stem II2 and exhaust valve I|0 to effect the movement of the supplyvalve I I3 toward the left against the opposing pressure of the spring I I4, unseating the valve LII'S. Fluidun'der pressurein chamber ||5 may new flow past the unseated valve. I 3 into chamber I0 pand thence. by way of passage |02 to chamber `|423 in thebrake cylinder device 9. When the pressure ofiluid' in chamber IOI together with: the pressure of the spring. I I4 becomes sufficient 15o-prevail over the pressure of iluid in chamber @fi/acting on.. diaphragm 93, diaphragm |00 will act through the medium of its follower |01 to shift vthe thrust member |04 toward the right, thereby permitting the spring |I4'to move the ,valveA I i3: into seating engagement withthe-supportfmeinber Referring to Fig. 1, it will beunderstoodthat the: pressure of fluid in chamber I2| vand acting over the. full.' area of the brake cylinder piston |20 will .prevail over the opposing pressures of the spring' i2? and of .the fluid in chamber |23, acting over that portion ofthe piston |20 which serves to define chamber |213, in an amount suflicient to transmita braking forceto the brake'rigging for raking an empty vehicle to the vdegree called for by the degree of reduction in brake pipe pressure. By. reason of the self-lapping arrangement ofthe valvesv in the relay valve mechanism 51 a constant proportionof back pressure to the pressurer in chamber: |I2I will be maintained in chamber |23 of .thexbrakecylinder device 9. If the-degree of back pressure should exceed the predetermined proportion, .this excess pressure acting in chamber Isl orrthe diaphragm |00 will cause the diaphragm to deflect to the right as viewed in Fig. 2, carrying the valve seat I091formed on the end of the follower member |04 away from sealing engagement with theI exhaust valve I|0. Fluid under' pressure in chamber I0 I Will then flow past thel valve seat: |09 through the bore and passage |58 to' chamber 9'8-and thence to atmosphere by -way oflpassage-SQ. When this flow of lfluid reduces the pressure' of fluid in chamber |0I tothe predetermined'degree, the diaphragm 93 will act `i-ri response'to the pressure of fluid in chamber 94 to return the valve seat |09 to seated engage- -ment with the valve I I0.

'Release of. the brakeswith the equipment conditioned for empty car operation '|33 to the retaining valve device 1, which connects pipe |33- directly to atmosphere when a handle |34 thereofl is in the position in whichfit isvshown. Brakecylinder device 9 now responds chamber |9I acting on the diaphragm |00 will l'cause' the diaphragm' to function in the'manner 'tothe release of fluid under pressure therefrom inthe'usual Iman-ner to eiect a release of the fvehicle brakes. Upon the yrelease of fluid under 'pressure from the chamber I2I, fluid under pres- -sure will-also be released from the chamber 94 of the relay va-lve mechanism 51 by way of the passage-'95, tube 96, passagefg'l, chamber 88, passage II'I, and passage H8. Upon release of fluid under lpressure'fromA chamber 94, the uid pressure in previously described to release uid under pressure from vchamber |23 to atmosphere by way of pas- Vchamber98 and passage 99.

sage |02, chamber'IOI, bore and passage |08,

.Automatic changeover4 operation of the equipare applied and that the vehicle is separated from the ,train and that while the brake pipe is at atmospheric pressure, lading is placed on the body of the vehicle. Under the inuence of such additional weight, the vehicle body and consequently the body parts I2, Bowden wire and measuring element I0, Will move downwardly relative to the xed surface I5 by reason of the usual truck springs (not shown) yielding to the additional weight.

Now when the vehicle is connected in a train, the brake pipe starts to charge With fluid under pressure in the same manner as hereinbefore described in connection with the charging of an empty vehicle. As before described, fluid under pressure which is supplied to the brake pipe I ows by way of pipe 32 to chamber 3| in the cutoi valve device E, whence it flows by way of tubular valve seat member 36, chamber 28 and passage and pipe 29 to chamber 49 in the load measuring cylinder 39. In response to the pressure of iluid in chamber 49 of the load measuring cylinder 30, piston 48 will move outwardly in the direction of the right hand against the opposing pressure of the spring 52, thereby causing the levers 6| and I3 to rotate or rock in a counterclockwise direction. As previously described, .this movement of the lever 6| will cause the cam member 60 to move outwardly and thereby effect the disengagement of the pawl 'I3 and dog 14. It will be understood that just prior to this action the cam member 60 also acted throughy the engagement of the surface 85 with a strut 86 to move the valve 81 in chamber 88 from its upper seated position to its lower seated position and thus to close oli' the supply of uid under pressure from passage and thereby connected chamber |2| of the brake cylinder device 9, and' out undue wear or damage while the brakes on f the vehicle remain applied. As a result of the additional deflection of the truck springs in response `to the additional `weight of lading on the vehicle, the measuring element I will be further removed from the surface I and consequently the lever I3 will be permitted to rock in a greater arc and the lever 6| to which it is positively coupled will likewise rock through a greater arc. The lever 6| will act through the medium of the pin 03 to shiftI the link 54 toward the left hand, the link engaging the pin 6B at the right-hand end of the slot 65 and rocking the lever 51 in a counter-clockwise direction about the pin 68. rhe lever -81 :will act through the \medium of the pin 59 to move the bar 59 and associated diaphragm carrying member 9| and diaphragm 93 outwardly relative to the abutment |05 for a distance commensurate with the distance which the car body and measuring element I0 have moved downwardly, from the surface I5 of the vertically fixed part on the truck in response to the weight of the lading added to the vehicle.

When the brake pipe pressure is increased to the degree required to eiect the operation of the cut-oir valve device E, this device will operate as described before to vent fluid under pressure from the chambers 3|, 28 and 49. With the chamber 49 thus vented, the piston 48 and the stem 53 of the load measuring cylinder Iwill respond 12 to the force of the spring 52 and move inwardly to the position in which they are shown. As a result of this movement the measuring element i0 will be retracted from engagement. with the surface I5 and the connected levers I3 and 6| will be rocked in a clockwise direction. Clockwise rocking of the lever 6| will cause the cam member 60 to be shifted inwardly causing the valve 87 to move to its upper seated position to close the atmospheric communication and again connect passage I|'| to the chamber 94, and also permitting ,the spring 18 to again actuate the dog 'I4 into operative engagement with the pawl 73. It will be remembered that the pawl 'I3 under the influence of the spring 'I1 had previously been actuated into locking engagement with bar 59 when the boss 82 of the cam member 60 passed to the right of the ball 813. It should be noted that movement of the cam member 60 in an inward direction carries the ball 83 out of engagement with the stem 84 so that the ball does not operate to disengage the pawl I3 from the tooth portion 79. Consequently, the bar 59 and the diaphragm carrying member 9| |will remain in their load adjusted position.

With the diaphragm carrying member 9| and diaphragm 93 positioned as just described, the variable load valve mechanism 8 is now in condition for braking the :Vehicle according to the weight carried by the vehicle.

Application of the brakes on a partially loaded vehicle When an application of the brakes is made on a partially loaded vehicle by eiecting a reduction in brake pipe pressure, the operation of the brake controlling valve device 3 will be identical with the operation described' for an empty ve-A hicle. From this it will be understood that iluid under pressure will be supplied through pipe |22 to the brake cylinder device 9 and from chamber |2I therein to chambers 94 and ||5 in the relay valve mechanism 5'| by way of passages I I8 and I I I in a manner previously described for the application of the brakes on an empty vehicle.

The pressure of fluid in the chamber 94 tends to deflect the diaphragm 93 and shift the iollower |05 toward the left against the pressure of the spring I I4. lit will be understood that the diaphragm carry-ing member 9| w-ill now be in some position to the right of that which it is shown rin Fig. 2 by reason of which the diaphragm 93 may not engage as much of the surface |06 of the mov- 'able abutment |05, as when braking an empty vehicle Ias shown in Fig. 2. When the pressure of fluid in chamber 94 is sufcient to overcome the pressure of t'he spring |4, the thrust member |04 will be Vcaused through the medium of movable abutment |05 to move to the -left land act through the medium yof .the follower |0'|,valve I I0 and Istem ||2 to unseat the supply valve IIB. Fluid under pressure in the chamber |2| of the brake cylinder device 9 will now flow by way of passages I I8 and II?, chamber ||5, passage ||6 and passage |02 to chamber |23 at the opposite side of a piston |20 in the brake cylinder device 9 to thereby reduce the effective force exerted on the piston |20 by the iluid pressure in chamber I2|. When the pressure of fluid in the chamber |0I, and consequently in the chamber |23, acting on the diaphragm |00 is sunicient to overcome the opposing pressure of uid in chamber 94 acting, through the medium of the diaphragm 93, over that portion of the surface |05 now engaged by the diaphragm 93, thrust member |04 will be caused by the diaphragm |00 and fclllo'w'er |01 to moveto the right and permit thesp'ring" I I4to move the valve |3 into seating engagement with the mem-` ber thus closing the passage IIB. Since the area of the diaphragm 93; ,which effectively engages the movable adjacent surface |06 of the movable abutment |05 is now less, it will be ap parent that the opposinguid pressure in chamber IUI required .to balance with the pressure of fluidin chamber 94 will now be less. With the pressure of' fluid in connected chambers I0! and '|23 fora given reduction .thuis reduced accord-ing to the load on the vehicle, the effective force eX- erted bythe pistor'l |20 in the brake cylinder yele-- vice 9 f-or -a given reduction will therefore be increased according to the Weight `of vthe lading on the vehicle.

Release of a service application of thebrakes on a partially loaded vehicle When it-is desired to effect a release of the brakes of a partially loaded vehicle, the brake pipe pressure is increased i-n the usual manner, causing the brake controlling valve device 3 to functionto establish communication from the chamber |2| in the brake cylinder device 9 to atmosphere by Way of the retaining valve device l. Fluid under -pressure now flows by way of pipe A|22 from the 'chamber`I`2I in the'brake cylinder device to the brake controlling valve device 3, and from there by Way of pipe |33 to the retaining valve device '1 which connects pipe' |33 directly to the atmosphere. As th'e pressure of iiuid' in chamber |2| is thus reduced, fluid under pressure in chamber 94 'flows by way of passage 95, tube 9B, passage 91, ,chamber S8, passages and||8 to chamber |2| and-thence to atmosphere by the route just described. When the pressure of fluid in chamber 94 is thus reduced the pressure of uid in 'chamber IEll will act through the medium of its follower |01, to shift the valve seat |09 out of kengagement with the valve I I0. Fluid under pressure will then flow' from chamber |23 in the brake cylinder device 9 to atmosphere by way of the passages |02 and IIB, chamber |0|, past the unseated valve H0, through the bore and passage |08 to chamber 98, and thence to atmosphere by way =of passage 09. With the pressure of uid :thus

released from chamber |2| in the brake cylinder device 9 the spring |21 will move the piston |20 to the position in which it is shown in Fig. 1, thereby elfecting a release of the vehicle brakes 'in' the usual manner.

Application and release of brakes-,fully loaded. e

'vehicle when me vehicle is muy ioaded and the brake pipe is charged from atmosphere, the measuring been shifted by the spring 92 to the position in4 which it is shown in the drawing and thereafter shifted to its fully loaded position. Upon a subsequent applicationof'tlie brakes being eifecte'd in the usual manner, fluid under pressure will again Vflow to chamber |2| in the brake cylinder device 9 and from there to chamber 94 in relay valve mechanism 51 in t'he manner previously described. New, however, fluid under pressure in chamber "Q4 will have no effect upon the relay valve mechanisln 51, since the carrying member 9| in its extreme right-hand position will loeate the diaphragm 93 so that it may engage the movable abutment |05 tangentially only. The' thrust member |04 will not be actuated out ofthe position in which it is shown in Fig. 2 and Iconsequently the valves ||0 and ||3 will remain seated as shown. The full .amount of iiuid under pressure suppliedy by t'he brake oonrtrolling vla'lve device 3 for applying the brakes will be delivered to chamber |2| only, and will become effective over the whole area of a piston |20, and the brake cylinder device 9 `will exert aforce on the brake shoes sumcient to brake a fully loaded vehicle. rihe .fluid in chamber |23 displaced by the outward movement 'of the piston |20 Will flow by way of passage |02 to chamber |0| where it will act upon the diaphragm |00 so as to effect the uri-seating of the valve |,|0. With valve ||0 unseated fluid under. pressure in chamber |23 will be exhausted to! atmosphere by way of passage les, chamber |0|, past valve I0, through passage |08, chamber 98 andpassage 99.

DESCRIPTION or APPARATUS SHOWN IN FIG. 3

As previously' sta-"ted, when-the variable load valve mechanism sh0vvninFigs.- 1 and 2Y is conditioned for .braking anl empty vehicle, aV portion of the fluid under pressure supplied from the brake controlling valve device 3' to the chamber |2| in the brake cylinder device 9 is admitted to the chamber |23'before the vpiston |20 moves outwardly. Then as the piston moves outward a part of the fluid in chamber' |23 is` vented Vto atmosphere by-the operation ofthe relay valve mechanism 51. It will be apparent therefore that, since the amount 'of fluid under Vpressure utilized .by the brake cylinder device'Q decreases as the load increases, the pressure at whichv the iluid pressure in the auxiliary reservoir-d equal-mes with chamber I2| upon approximately a twenty pound or full service reduction in brake pipe pressure, or, the pressure at ,which the fluid vpressure `-infbcth auxiliary and emergencyV reservoirs equalize with the chamber |2| upon an emergency reduction in brake pipe pressure, increases as the load increases. If for .any reason it should be desired to obviate this result a modified form of the invention may be provided.

In Fig. 3 this modified form of the `invention is illustrated whereby the uid under vpressure delivered by way of passage |02 to chamber |23 of the brake cylinder device 0 is supplied from a supplementary*reservoir |35 which is arranged to be charged with fluid under pressure from the brake pipe and is entirely separate from the brake controlling valve device 3V and its associated reservoirs 4 and 5. In this formV of the invention the variable load valve mechanism |35 is substantially the same as the load valve mechanisrn 8 shown in Figs. 1 andl 2, the dilerence residingI in the communications to the chamber ||5 which chamber Was described in connection 'with the variable load valve mechanism 8 shown in Fig. 2. As shown in Fig. 3, chamber |I5 of the variable load valve mechanism |36 is in constant open communication with the supplementary reservoir |35 only, the communication being f effected by means of a passage and pipe |31. For

supplying fluid under pressure to the reservoir |35 the brake pipe is connected to the pipe |31 by Way of a pipe |38, check valve |39 and pipe |40, thecheck valve permitting the ow of iluid under pressureonly in a direction away from the brake pipe and toward the reservoir.

i OPERATION or THE APPARATUS SHOWN 1N FIG. 3

|35 by way of a -pipe |138, a check valve |39, a pipe v |48 and the pipe |31.

When it is desired to effect an application of the brakes, the brake pipe pressure is reduced in the usual manner, causing the brake controlling valve device 3 to operate in the same manner as hereinbefore described. Fluid under pressure supplied from the auxiliary reservoir 4 to chamber |2| in the brake cylinder device 9 will flow by way of passages ||8 and and the control diaphragm chamber S4 of the relay valve mechanism |4| of the variable load valve mechanism |36. I f the apparatus is conditioned for braking an empty or partially loaded vehicle, the relay valve mechanism |4| in response to the pressure of fluid thus supplied will operate the self-lapping valve arrangement therein to supply fluid under pressure in chamber l5 to the pressure chamber |23 in the brake cylinder device 9. Since chamber |2| is not connected in this case to chamber |55, this iiow will have no effect on the pressure of uid in chamber |2|. Consequently the pressure of fluid in chamber |2| at the point of equalization or full service reduction in brake pipe pressure Will be the same each time regardless of the load condition of the vehicle. Likewise the pressure of uid in chamber |2| will be the same for each emergency application regardless of the load condition of the vehicle.

SUMMARY By the use of this invention it will be seen that there is provided a variable load apparatus which will operate in conjunction with the standard AB freight brake equipment Without necessitating any changes therein. When the brake pipe pressure has previously been reduced to atmosphere in the usual manner, the .cut-off valve device 6 is conditioned at approximately 20 pounds brake pipe' pressure to supply fluid under pressure, delivered thereto from the brake pipe, to the load measuring cylinder Si) of the variable load valve mechanism 3. Upon charging the brake pipe above atmospheric pressure in the usual manner, fluid delivered by way of the cut-olf valve device acts on the load measuring mechanism 30 to actuate the measuring element IQ into engagement with the surface l5 of a vertically stationary part of the vehicle. At the same time the adjusting mechanism 56, in response to the operation of the load measuring `cylinder 3B, unlocks the diaphragm positioning bar 5S and positions it according to the degree of travel of the measuring element lil, the travel of the measuring element IB and the displacement of the diaphragm carrying member 9| and diaphragm g3 to the right from the position in which it is shown will increase as the weight of the lading on the vehicle increases. When the brake pipe pressure is increased to approximately 50 pounds the cut-olf valve device will interrupt the supply of fluid under pressure to the load measuring cylinder 3|) and vent the uid under pressure already supplied thereto to at- Inosphere. Now when an application of the brakes is effected, fluid under pressure is supplied from the brake controlling valve device 3 by way of the pipe |22 to the piston chamber iii at one side of the brake cylinder piston |20 and the control diaphragm .chamber 94 in the relay valve mechanism 51 of the variable load valve mechanism. In response to the pressure of fluid thus supplied, the relay' valve mechanism 51 will operate the self-lapping valve arrangement therein to supply a portion of the fluid under pressure supplied thereto to the pressure chamber |23 at the opposite side of the brake cylinder piston thereby reducing the effectiveness of the piston |20. 'I'he degree of activity of the relay valve mechanism, and consequeny the amount of fluid under pressure supplied to the chamber |23 of ythe brake cylinder device 9, decreases as the diaphragm =93 is displaced to the right by the diaphragm carrying member 9|. The proportionality, or relation, between the amount of fluid supplied to the chamber |23 and the degree of displacement of the diaphragm 93 may be directly, that is, in a straight line characteristic, or may be given other characteristics by the simple 4expedient of changing the shape of the surface |06 of the movable abutment |05.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A fluid pressure control mechanism comprising a casing having Ia chamber to which uid under pressure may be supplied and in which the pressure of iiuid may be varied to effect the control of a device to be controlled, valve means operative to admit fluid under pressure to said chamber, a control element operatively engaging said valve means and being responsive to a control fluid pressure -to admit uid under pressure to said chamber, means subject to the pressure of uid in said chamber and operative to actuate said valve means to cut off the supply of fluid to the chamber when the force of the means exceeds the actuating force of said control element, said `control element being movable relative to said valve means to different positions to produce different actuating forces on said valve means in response to a given control iiuid pressure, and means operative to move said control element relative to said valve means.

2. A iiuid pressure control mechanism comprising a casing having a chamber to which fluid under pressure may be supplied and in which the pressure of fluid may be varied to effect the control of a fluid pressure responsive device to be controlled, valve means operative to admit fluid under pressure to said chamber, control means responsive to fluid pressure for actuating said valve means to admit iiuid under pressure to said chamber, means responsive to the pressure of uid in said chamber and acting in. opposition to the pressure of iiuid acting on said control means for effecting the operation of said valve means to cut off the supply of fluid under pressure to said chamber, and a member shiftable relative to said valve means for moving said control means to different positions to correspondingly vary the effectiveness of the control means to actuate said valve means.

3. A uid pressure control mechanism comprising a casing having a chamber to which iiuid under pressure may be supplied and in which the pressure of iiuid maybe varied for effecting the control of a device to be controlled, valve means operative to supply iiuid under pressure to said chamber, a movable abutment constituting a part of said valve mechanism and having a substantially convex end face, control means for actuating said valve means, said control means comprising a diaphragm operatively engaging said end face of the movable abutment and being responsive to a control fluid pressure for actuating said abutment and thereby said valve means, and said diaphragm being movable relative to said abutment to different positions to provide different areas of engagement betr/een the diaphragm and the end face of the abutment, a member mounted in said casing and carrying said diaphragm and being movable relative to said casing for positioning said diaphragm with relation to said abutment, and means subject to the pressure of fluid in said chamber yieldably opposing the operation of said valve means by said diaphragm and operative to effect the operation of said valve means to cut off the supply of fluid to said chamber when the force of said means exceeds the actuating force of said diaphragm.

4. A duid pressure control mechanism comprising a casing having a chamber to which fluid under pressure may be admitted and from which fluid under pressure may flow to a device to be controlled, valve means operative to admit fluid under pressure to said chamber, control means movable to different positions relative to said valve means and operative in its different positions to actuate said valve means to admit fluid under pressure to said chamber, said control means comprising a flexible diaphragm responsive to a control pressure for actuating said valve means, said diaphragm and valve means cooperating in the different positions of the diaphragm to establish different effective pressure areas for the diaphragm, and means subject to the pressure of iiuid in said chamber and operative when the force of said means exceeds the force of said diaphragm to effect the operation of said valve means to cut off the admission of uid under pressure to said chamber.

5. A fluid pressure control mechanism comprising a casing having a chamber to Which fluid under pressure may be admitted and in which the pressure of' fluid may be varied to effect the control of a device to be controlled, valve means operative to admit fluid under pressure to said chamber, control means movable to different positions with relation to said valve means and operative in its different positions in response to a control fluid pressure to actuate said valve means to admit fluid under pressure to said chamber, said control means and said valve means cooperating in the different positions of the control means to establish correspondingly different ef. fective areas of control means over which the control fluid pressure acts to actuate the valve means, and means subject to the pressure of fluid admitted to said chamber yieldably opposing the force exerted on said valve means by said control means and being operative when the force of said means exceeds the actuating force of said control means to actuate said valve means to cut off the admission of iiuid under pressure to said chamber.

6. A fluid pressure control mechanism comprising a casing having a chamber to which fluid under pressure may be admitted and from which uid under pressure may fioW to a device to be controlled, valve means operative to admit fluid under pressure to said chamber, a member mounted in said casing and being movable relai8! tive to said valve means, said member having a control chamber to which fluid under pressure may be supplied, a control element carried by and movable with said member to different positions relative to said valve means, said control element in its different positions being operative relative to said member in response to the pressure of fluid supplied to said control chamber for actuating said valve means, the control element and valve means cooperating in the different positions of the control element to condition the control element to exert correspondingly different actuating forces on said valve means in response to any given fluid pressure in said control chamber, and means subject to the pressure of fluid inthe first mentioned chamber yieldably opposing the operation of said valve means by said control element and being operative when the force exerted by said means on said valve means exceeds the force exerted by said control element on said valve means for actuating said valve means to cut olf the admission of uid under pressure to the first.v mentioned chamben l 7. A fluid pressure control mechanism comprising a casing having a chamber to Which fluid under pressure may be supplied and in which the pressure of fluid may be varied to eliect` the control of a device to be controlled, valve means operative to admit fluid under pressure to said chamber, a control element operatively engaging said valve means and being responsive to a control iiuid pressure for actuating said valve means to admit fluid under pressure to said chamber, means subject to the pressure of huid insaid chamber and operative to actuate said valve means to cut ofi the supply of fluid to the chamber when the force of the means exceeds the actuating force of said control element, said control element being movable relative to said valve means to different positions to produce different .actuating forces on said valve means in response to a given control fluid pressure, and said means being operative in response to a reduction'in'the control fluid pressure acting on said control element for actuating said valve means to eiect a reduction in the pressure of fluid in said chamber, and means operative to move said control element relative to said valveV means.

8. 1n a vehicle variable load fluid pressure brake equipment, a brake cylinder device, means operative to supply fluid under pressure to effect the operation of said brake cylinder device to apply the brakes, and means operative in response to the pressure ofv fluid being supplied to the brake cylinder device to cause a force to be established to oppose the brake applying operation of the brake cylinder device, the second mentioned means being conditionable according to different weights of load carried by the vehicle to create correspondingly different forces to oppose the brake applying operation of the brak-e cylinder device.

9. In a vehicle variable load fluid pressure brake equipment; a brake cylinder, a brakepipe normally charged with fluid under pressure, means operative upon a reduction in brake pipe pressure to supply uid under pressure to vthe brake cylinder to effect an application of the brakes, and means operative in response 'to' the pressure of fluid supplied to the brake cylinder to supply duid under pressure to' establish a force in opposition to the action of the brake cylinder and thereby control the brakinggforce exerted by the brake cylinder, said meansgbeing conditionable according toA different' Weights of 119 load :carried :by the vehicle for operation to regulate the -supply of, fluid to establish .correspondingly.different forces in opposition to the action of thebrake cylinder.

10. .In a -vehicle lvariable load fluid pressure brak-e equipment, a "brake cylinder device comprisingacylinder and a piston operatively mounted:-in.said cylinder for operation to effect an application of the brakes, said piston dividing the .cylinder-into two fluid receiving chambers, means `operative .toadmit fluid Aunder pressure to vone vbrake cylinder chamber to cause .said piston to operate to effect Vthe application of the brakes, andi-means operativein response to the pressure ofuid-admitted tosaid one brake cylinder chamber for admitting iluid under pressure to the otherbrake cylinder chamber'to modify the braking force-exerted by said piston, said means being .conditionable according to different IWeights of the load Y.carried .by the vehicle to operate to admit .correspondingly diiferent pressures of duid to said ether brake cylinder chamber.

11. In la `vehicle variable load fluid pressure brake equipment, a brake cylinder device comprising-a-cylinder and a piston operatively mount- .edLinfsaid cylinder for operation to effect an applicationof the brakes, said piston dividing the cylinder into two fluid receiving chambers, means operative to admit fluid .under Apressure to one brake cylinder chamber :to cause said piston to operate .to Yeffect an :application .of the brakes, .valve-means operative toiadmitiluid under pressure-:tofthe other :brake cylinder chamber to exert an :opposingforceton said piston, control means responsive to the pressure of fluid `in said Vone brake :cylinder chamber for actuating said valve means to:a;dmit iluid underpressure to said other brake cylinder chamber, and means subject to theLpressure of .fluid admittedito'said other .brake cylinder chamber to opposeithe operation of said valve means and operative Whenthe opposing force tof themeans exceeds the force of the said control v:means .to cut off the .admission Aof ifluid under :pressure to said other chamber, said control -means .being conditionable vaccording to -different weightsof .lading carried by the `vehicle totransmit differentactuating forcestosaid valve means undertheinfiuence ofga givenfluid'pressure facting thereon.

:112. In fa :variable loadbrake equipment for vehicles,?brake controllingmeans operative by fluid under :pressure to effecten application ofthe brakes, yvalve means operative .to supply fluid under pressure `for actuating 'said brake controlling imeans, means adapted to be subjected to pressure Yofiluid to ,yieldably oppose theoperation of :the .'brakecontrolling means andthereby modifythebraking force exerted bythe brake controlling-means, and control means operativein re- `spouse vto rthe pressure of fluid being Ysupplied `to'said brake controlling means vfor subjecting said means to pressure of fluid and to control the fdegreeo'f pressure fluid to which the means is subfije'cted, .fsaid control means being conditionable .according to diiferent Weights of lading carried byithe'vehicle'for voperation to cause said means :tome-subjected to different degrees vof'iluid presfsure. Y

113. Infazvariable load lbrake equipment for vehicles,brakecontrolling means operative lby fluid Aunder vpressure :to -eiect an application -of the `brakes, 'valve vmeans operative to supply .fluid underpressurefor actuating said brake 'controlllingmearts,'means adapted to be subjected to .the pressure of "fluid to yieldably oppose 4the operation of the brake controlling means and thereby modify 'the braking force exerted bythe brake controlling means, and control means operative in response to the pressure of fluid being supplied to said brake controlling means for subjecting said means tothe pressure of fluid .and to control the degree of pressure to which the means is subjected, said control means being variousll7 conditionable to operate to cause said means to be subjected to different degrees oiluid pressure, and means operative according to different Weights of lading carried by the vehicle for conditioning said control means.

14. In a variable load brake equipment for vehicles, brake controlling means operative by ud under pressure to effect an application of the brakes, valve means operative to supply fluid under pressure for actuating said brake controlling means, means adapted to be subjected to the pressure of fluid to yieldably oppose the operation of the brake controlling means and thereby modify the braking force exerted by the brake controlling means, and control means operative inresponse to the pressure of fluid being supplied to said brake controlling means for subjecting said means to the pressure of fluid and to control the degree of Vpressure to Which'the means is subjected, said control means being conditionable when the vehicle is empty to cause said means to be subjected to a certain maximum degree of fluid pressure and being .conditionable whenthe vehicle is partially loaded to cause the means to be subjected zto a lesser degree of fluid pressure, and being rendered ineilective, when the vehicle is heavily loaded, to `operater to'subiect said means to the pressure of fluid.

15. In a variable load brake equipment for vehicles, Vbrake controlling means operative by fluid under vpressure 'to effect an application Yof the brakes, valve means operative to supply fluid under pressure for actuating said brake controlling means, means adapted to be subjected to the pressure of fluid to yieldably oppose the operation of the brake controlling means and thereby modify the braking force exerted bythe brake controlling means, and control means operative in response to the pressure of fluid being sup.- plied Vto said brake controlling means for subjecting said means to the pressure of fluid and to control the degree of pressure to which the means is subjected, said control means being variously conditionable to operate to cause said means to be subjected to different degrees of fluid'pressure, and means operative when the vehicle is empty or partially loaded to condition said `mechanism and operative when the vehicle is lheavily loaded for rendering said control means ineffective to operate to subject said means lto fluid pressure.

-1'6. `Ina variable load brake equipment for vehicles, in combination, a brake cylinder comprising a cylinder and a piston operatively mounted in the cylinder for operation to effect an applica tion of the brakes, said piston dividing the cylinder into two fluid receiving chambers, means operative to supply fluid under pressure to one brake cylinder chamber to effect an application of the brakes, and means responsive to the'pressure of fluid admitted vto said one brake cylinder chamber to admit uid under pressure to the other brake cylinder chamber 'to oppose the effect `of :fluid under pressure in `said one brake cylinder chamber and being Yresponsive to .the pressure of fluid in `said other brake cylinder chamber for controlling the degree of pressure 21` in the said other brake cylinder chamber, said means being conditionable according to different weights of lading carried by the vehicle to provide correspondingly different degrees of fluid pressure in said other brake cylinder chamber for any given degree of fluid pressure in said one brake cylinder chamber.

17. In a variable load brake equipment for vehicles, in combination, a brake cylinder comprising a cylinder and a piston operatively mounted in the cylinder for operation to effect an application of the brakes, and piston dividing the cylinder into two fluid receiving chambers, means operative to supply fluid under pressure to one brake cylinder chamber to effect an application of the brakes, and means responsive to the pressureof fluid admitted to said one brake cylinder chamber to admit iluid under pressure to the other brake cylinder chamber to oppose the effect of fluid under pressure in said one brake cylinder chamber and being responsive to the pressure of fluid in said other brake cylinder chamber for controlling the degree of pressure in the said other brake cylinder chamber, said means being conditionable, when the vehicle is empty, for operation to provide a certain maximum degree of fluid pressure in said other brake cylinder chamber and being conditionable when the vehicle is partially loaded to provide a lesser degree of fluid pressure in said other brake cylinder chamber and being rendered ineffective, when the vehicle is to a greater degree loaded, to provide fluid under pressure in said other brake cylinder chamber, and a mechanism operative according to whether the vehicle is empty or loaded to condition said means for operation to control the pressure of fluid in said other brake cylinder chamber.

18. A vehicle fluid pressure brake equipment comprising a brake cylinder device having a piston operable to effect an application of the brakes and also having two chambers located respectively at opposite sides of the piston, means for supplying iiuid under pressure to one of said chambers for effecting the operation of said piston, valve means responsive to the pressure of iluid in said one chamber to supply fluid under pressure to the other chamber, and control means responsive to the pressure of fluid in said other chamber to cut off the supply of fluid under pressurethereto, said control means including a diaphragm which responds to the pressure of fluid in said other chamber to operate said valve means and which is shiftable to different positions relative to said valve means to cooperate with the valve means for varying its effective area.

19. A vehicle fluid pressure brake'equipment comprising a brake cylinder device having a piston operable to effect an application of the brake and having two chambers located respectively at opposite sides of the piston, means for supplying fluid under pressure to one of said chambers for effecting the operation of said piston, valve means responsive to the pressure of fluid in said one chamber to supply fluid under pressure to the other chamber, control means responsive to the pressure of fluid in said other chamber to operate said valve means to cut 01T the supply of fluid under pressure thereto, said control means including a diaphragm which responds to the pressure of fluid in said other chamber to operate said valve means and Which is shiftable to different positions relative to said valve means to cooperate wlth the valve means for varying its ef- 22 fective area, and means operative for` shifting said diaphragm to its different positions.

20. A vehicle fluid pressure brake equipment comprising a brake cylinder device having a piston operable to effect an application of the brakes and having two chambers located respectively at opposite sides of the piston, means for supplying fluid under pressure to one of said chambers for effecting the operation of said piston, a valve means responsive to the pressure of fluid in said one chamber to supply fluid under pressure to the other of said chambers, and means responsive to the pressure of fluid in said other chamber to actuate said valve means to cut off the supply of fluid under pressure to the chamber and being operative as the piston moves to effect an application of the brakes to vent fluid under pressure from said other chamber to thereby insure against an increase in the pressure of fluid in the chamber due to the brake applying movement of the piston.

21. In a iluid pressure brake equipment, a brake cylinder device comprising a casing, a piston operatively mounted in said casing and dividing the cylinder into two fluid receiving chambers, means operative to supply fluid under pressure to one brake cylinder chamber for effecting the operation of said piston to apply the brakes, valve means responsive to the pressure of fluid being supplied to said one brake cylinder chamber to supply fluid under pressure to the other brake cylinder chamber, pressure sensitive means responsive to the pressure of fluid being supplied to said other brake cylinder chamber to actuate said valve means to cut off the supply of iluid to the -other chamber and being also operative in response to an increase in the pressure of fluid in said other brake cylinder chamber, incident to the movement of the piston in the brake applying direction, to vent fluid under pressure from the other chamber.

22. In a vehicle fluid pressure brake equipment, a brake cylinder device comprising a casing, a piston operatively mounted in said casing and dividing the casing into two brake cylinder chambers, means operative to supply fluid under pressure to one brake cylinder chamber for effecting the operation of said piston to apply the brakes, valve means responsive to the pressure of fluid being supplied to said one brake cylinder chamber for supplying fluid under pressure to said other brake cylinder chamber to yieldably oppose the movement of said piston in its brake applying direction, and means responsive to a predetermined increase in the pressure of fluid in said other brake cylinder chamber for actuating said valve means to cut off the supply of fluid under pressure to the chamber, and being operative in response to a further increase in the pressure of fluid in the chamber incident to the movement of said piston in its brake applying direction, for venting fluid from the chamber to dispel said further increase and thereby maintain the fluid in the other chamber at substantially the said predetermined pressure.

23. In a vehicle fluid pressure brake equipment, a brake cylinder device comprising a casing, a piston operatively mounted in said casing and dividing the casing into two brake cylinder chambers, means operative to supply iluidunder pressure to one brake cylinder chamber for effecting the operation of said piston to apply the brakes, valve means responsive to the pressure of fluid beingsupplied to said one brake cylinder chamber for supplying fluid under pressure to said other brake cylinder chamber to A yieldably oppose the movement'of said pistonin its brake. applying die rection, and a flexible diaphragm responsive to a predetermined increase in the pressure of iiuid in said other brake cylinder chamber for actuating said valve means to cut oi the supplycf uid under pressure to the chamber, said piston in its movement in the brake applying direction increasing the pressure of fluid in the chamber above said predetermined pressure, Asaid diaphragm being responsive to the increase in the pressure vof 'fluid in the chamber above said pren determined pressure for venting'iiuid under pres sure rfrom the chamber to maintain the fluid in the chamberiat substantially saidrpredetermined pressure for the full travel vof said piston in its brake applying direction,

24. In a vehicle fluid pressure brake equipment, a brake cylinder device comprising a casing, a piston operatively mounted in said casing and dividing the casing into two brakescylinder chamu bers,means operative to supply fluid under pressure to one brake cylinder 4chamber for Veifectmg the operation of said piston to apply the brakes, valve means responsive tothe pressure oi fluid being supplied to said one'bra'ke cylinder chamber forsupplying 'fluid under pressure to said other brake cylinder chamber to yieldably oppose the movement of said piston in its braise applying direction, land a flexible diaphragm respon sive toa predetermined increase in the pressure of `iiuid in said other brake cylinder chamber for actuating said valve means to Vcut ofi the supply of fluid underl pressure to the other chamber, said piston in its movement in the brake applying direction increasing the pressure of 'fluid `in the other chamber above said predetermined pressureysaid diaphragm being responsive'to the increase in thepressure of uid in the other chamber `above said predetermined pressure for venting fluid under pressure from the other chamber to Ymaintain the iiuid in the other chamber at substantially said predeterminedpressure for the full .travel of said piston in its brake 'applying direction,'and means for actuating said valve means to cut oiithe venting of iiuid under pressure from said other brake cylinder chamber when said piston Vreaches the end of vits brake applying travel.

25.`In a control'mechanism for a fluid pressure system, said mechanism comprising a `casing having a fluid pressure inlet passage to which -flllid under pressure'may be supplied and also having a, duid pressure outlet-passage through which fluid'underpressure may be admitted to a Vdevice to be controlled, valve means operative in one Vdirection Yto supply iiuid under pressure fromsaid'inlet 'passage to-said outlet passage, and operativein the `opposite 4direction to cut off the supplyof fluid'under pressure from said inlet passage to saidoutlet passage, a rst flexible 'diaphragmpperative by fluid under pressure in said inlet passage for actuating said valve means in said one direction, a second flexible diaphragm operative by fluid under pressure being supplied to said outlet vpassage for Yactuating ysaid valve means in said opposite vdirection vWhen the force exerted 'on'the'valve means by the second diaphragm exceeds the -`force'exerted onthe valve means 'by 'said' rst diaphragm, Atvvo spaced stops carried by said casing, a member mounted in said casing for movement between saidV stops and carrying said rst diaphragm, said first diaphragm When said member is in engagement with one of said'stopabeingroperative to Vexert-a certain maximum actuating forceon said valve means -and said rst diaphragm when saidfmemberiis inengagement with the other of said stops being rendered ineffective to actuate said valve means, said first diaphragm, with said member in any lposition intermediate said stops, exerting an actuating force on said valve means less than saidcertain'maximum force, a valve having one position in which uid under pressure fromsaidrinlet passage is supplied Ato act on said lfirst diaphragm and having a second position in Whichthe supply of fluid to act on the said first diaphragm is cut off and the fluid under pressure acting on the second diaphragm is vented, means locking -said member against movement relative'to said valve means, means operative to actuate saidvalve from its said first position lto its said second position and to then actuate the locking means to'unlock said member and nally to move said member, an'dthereby-said'rst diaphragm, said means being subsequently operative to first effect'the operation of said vlocking means to'lock said'rmem- -ber and diaphragm in the position to which they have been moved and to then effect the 4movement oi said valve to its said rst position.

26. n a fluid pressure control valve device comprising a casing having a fluidpressureinlet passage and afluid pressure outlet'passage, valve means operative to supply fluid under 4.pressure from said inlet passage to said outlet passage, means for actuating said valve means, saidv means comprising anelement responsive'to the pressure of uid in said inlet vpassage for actuatingthe valve means, a member operative to move saidelement relative to saidvalve -means to 'different positions, said element in its different positions exerting diierent actuating forces Von'saidvalve means for a given fluid pressure actingthereon, actuating means for said valve means subjectlto the pressure of fluid in said outletpassageiand operative, when theforce exerted thereby onsaid valve means exceeds the force'exerted on the valve means by said element, ton actuate the valve means to cut off the supply offluid under pressure 'to said outlet passage, Va valve having one position in which uid -underpressure from-said inletp'assage is supplied'to 'act on said element and havinganother position in which the supply of fluid under pressure to the element'is `cutoifandtl'le uid acting on the element-is discharged-to the atmosphere, locking means for engagement'with said member to lock the 'memberand therebysaid element in any particular oneof its'diierent positions, mechanism operative-inane directionjof movement to l'irst move saidvalve fromsaidione position to its otherA position, to then 'move said locking means out of locking engagement with said member and to then move saidmember 'to a particular position, means operative uponmovement of said locking Vmeans Yout of locking engagement with said member for moving themember in the direction toward said valve Vmeans Yto a given position, said mechanism beingoperative in the opposite `direction vof movement for first eiectingthe Voperation of said ,lockingymeans to lock said member in said particular'position'and to then effect the operation of said valve'from-its saidother position Ato its isaid one position.

27. In a fluid pressure .control `valve device comprising a casing having a'fluidpressureinlet passage and also having a fluid Apressure outlet passage, valve lmeans operative to one position to supply fluid under pressure `from said 4inlet passage to said outlet'passage and operative Lto another vposition to cut oi vthe--supplyfoif 4fluid under pressure to the outlet passage, an element movable to a plurality of different positions relative to said valve means and being responsive in any of its different positions to the pressure of fluid in said inlet passage to actuate the valve means to supply duid under pressure to said outlet passage, the force exerted by said element on the valve means for any given fluid pressure acting thereon being different in each of its positions, means subject to the pressureof iiuid i said outlet passage for actuating said valve means, when the force it exerts on said valve means exceeds the force exerted on the valve means by said element, to cut off the supply of uid under pressure to said outlet passage, a member carry-- ing said element and being slidably guided in said casing for moving the element to its different positions with relation to said valve means, a valve having a first position in which iiuid under pressure from said inlet passage is supplied to act on said element and having a second position in which the supply of uid under pressure to the element is cut off and in which the uid under pressure acting on the element is discharged to the atmosphere, a rst pawl engaging said member to lock the member against movement in a direction away from said valve means, a second pawl engaging said member to lock the member against movement in the direction toward said valve means, a mechanism operative to rst actuate said valve from its said first position to its said second position, to then actuate said first pawl to its unlocking position and to then actuate said second pawl to its unlocking position, means for moving said member and thereby said element in the direction toward said valve means upon movement of the said first pawl to its unlocking position, said member after itvhas been moved by said means being moved by said mechanism to a particular one of its diiferent positions, said mechanism being operative, when said member is in its particular position, to rst effect movement of said pawls into locking engagement with said member and to then move said valve from its said second position to its said first position.

28. In a variable load fluid pressure brake equipment for a vehicle, the combination with a brake pipe normally charged with fluid under pressure, a brake cylinder, and a brake controlling valve device responsive to a reduction in brake pipe pressure to supply fluid under pressure to the brake cylinder to cause the brake cylinder to operate to effect an application of the brakes, of valve means operative to supply fluid under pressure being supplied to said brake cylinder to oppose the operation of the brake cylinder in its operation to effect an application of the brakes and operative to cut off the supply of fiuid under pressure opposing the operation of the brake cylinder, a fluid pressure sensitive element operative in response to the pressure of fluid supplied by said brake controlling valve device for actuating said valve means to supply fluid under pressure, a member carrying said fluid pressure sensitive element and operative upon movement in the direction toward said valve means for rendering the element effective to exert a maximum actuating force on said valve means in response tc a given uid pressure acting on the element, and operative upon movement in the opposite direction for rendering the element effective to exert a lesser actuating force on the valve means in response to said given fluid pressure, means included in said valve means subject to the pressure of iiuid supplied by said valve means yieldably opposing the operation of the valve means by said element and operative when the force it exerts on the valve means exceeds the force exerted by said element for actuating the valve means to its cut off position, means locking said member against movement, a valve having one position in which said element is subjected to the pressure of fluid and having another position in which the supply of fluid under pressure to said element is cut off and in which the fluid under pressure acting on the element is discharged to the atmosphere, piston means operative by fluid under pressure being supplied to the brake pipe in initially charging the equipment to iirst actuate said valve from its said one position to its said other position, to then actuate the locking means to unlocking position and to then position said member and thereby said element relative to said valve means, a cut-off valve device operative in response to a chosen increase in brake pipe pressure for cutting oif communication between the brake pipe and said piston means and for venting fluid under pressure acting on the piston means said piston means being operative upon the venting of the fluid under pressure acting thereon for first effecting the operation of the locking means to lock said member and element in the position to which they have been moved and to then move said valve from its said other position to its said one position.

29. A variable control mechanism comprising a control element having a normal position and movable therefrom to various other positions of adjustment, resilient means constantly urging said control element toward its normal position, power means operative to move said control element out of said normal position to one of said various other positions of adjustment against the opposing force of 'said resilient means, a locking means for locking said control element in its adjusted position against movement in a direction toward its normal position, and means operative by said power means to render said locking means ineffective prior to the movement of said control element and to render said locking means effective at all other times.

30. A variable control mechanism comprising an element which may be adjusted for varying the control of said mechanism, said element having a normal position and being movable therefrom to various other positions of adjustment, resilient means constantly urging said control element toward its normal position, power means operative to actuate said control element against the opposing force of said resilient means out of said normal position gto apredetermined adjusted position, pawl means for preventing movement of said control element toward its normal position and operable to lock said element in its adjusted position, dog means for holding said pawl means in locking relation with said element, cam means operative as an incident to the movement of said power means for actuating said element to first render said dog means and then said pawl means ineffective, means for rendering said pawl means effective during the adjusting movement of said.

element to prevent movement of said element toward said normal position, and means operatively associated with said power means operative to render said dog means effective after said element has reached its predetermined adjusted position.

31. In a control mechanism for a fluid pressure system, in combination, a control member having a normal control position and being shiftable 2,45 deca.

motion-for,actuatingsaidflatching means to unlock.'Y

saidj control member during' the lost= motion 1novement1of-sa-id linkage-andthereafter to render said 1 latchingmeans eff ectiveto lock said control member in the position', to which'. ithas been shifted;

3,2-, In av controlmechanism-for; aiiuid pressure'. system, incombinatiom a control. member having ai. normal control positionand. being shiftable.

tl'ierefrom to various other. controll positions,

resilient. means. constantly urging. said control;

member toward its normalpositionra-fluid pressuremotor for actuating said member--toa predetermined1controlposition, a linkagev connecting:

lost: motion: movement of the motorand linkagev to' render the' locking means. temporarilyy in- Y effective.

33A' vehicle variable load` brake equipment comprising' a control elementhaving. an empty position and beingfmovabl'e therefrom to a pluralityv of:` other. positions for varying the braking power` of' theV brakeequipment according to thel loadxonthe'vehicle, power means operative'to' shift' said elementout of said' empty. position to a' po'sition'-determinedaccording to load,- resilient m'e'ans constantly' urgingv said' control; element toward; empty position, locking' means; for locking said element against movement, meansopera'- tivoby'saidpower means prior to. shifting said element; olr'ender 'said' locking' mean's'ineiective,

and'mea-n'siforrendering saidlocking means effec'- tivetuponmovement of'saidielement: out of empty` position' byfsaid. power' means:

34;.In acontrol mechanism fora fluid'pressure' system, in combination, acontrol member. having a norma-l control' position and being shiftable' therefrom' to various other controlpositicns, resili'ent. means constantly urging saidf control member.' toward its'. normal position, a fluid'pressure' motor' operablezin oney direction forv actuating said? control'. member: to a predetermined' control f position, .alink'age connectingsaid' motor. to said' control member. fori positioning the member, saidY linkage' comprising an element providingfor lost motion'linthe.preliminaryxoperation of 'said motor in". either direction', .pawl means' for' locking'said member: against' movement" toward' itsv normal position, a-do'gim'eans-ifor holding said pawlm'eans in'. lo'c'kingi relation" with' said' controli member,- aV canrm'ean'spositively connected Ato said'ilinkage' opera'tivecluringitl'ieflostmotionnio-vein'entiofsaid'` position to'` render 'said i pawl 1' means'. effective; and'v 28' means. for rendering'. said dog meanseiiective during; thefpreliminary operation of the motor in theopposite direction.

35.A Av vehicle variable load brake equipment comprisingga control element having an empty positiongand'being movable therefrom to a plurality of. other positions for varying the braking powerv of thej brake equipment according to the load' onthe vehicle; resilient means for urging said control element toward empty position, power means operativeto overpower said resilient means andshift said element out of said emptyposition.Y to. av positiondetermined according. to load, locking means for locking said ele- Vment, meansoperative by said power means upon... initial operationv thereof to render said locking ,meansineifective prior to shifting said element, andimeansfor rendering said locking means effectvefupon movement of said element out` of empty; position by said power means.

36:-Ir1 acontrol mechanismfor a fluid pressure system, incombination, a control member having' ar normal control position, resilient means urging 'said' controlmember toward its normal,y position, a: fluidpressure chamber in saidfmember, adiaphragm serving to define said chamberi andfresponsive'to pressure of fluid supplieditothe chamber to'cause said control member tofexer-t aforce in a direction away fromv its said-normalposition, valve means having a normal positionffor permitting fluid under pressure toflow to. said-.uid-pressure chamber and operativeto another. positioniinwhich the supply of fluidI under pressure'is cut off and said chamber is -ventedsto atmosphere, means normally 'locking said. member against movement, and means operativetofa-ctuatev said valve from its normal positionto-its other position, then to actuate said lockingmeanszto unlock said member, and finally toiactuate said control member to a predetermined` control position', the last mentioned meansfbeingisubsequently operative to first effect theoperation-of said.` locking means to lock said memberin the-position to which it has been movediandfthen to effect. the movement of' said valve yto.its..said .normal position.

37,;:A variable c-ontrolv mechanism comprising:l an adjustable-1control'meinber adapted to' be subjected. on; oneside to pressure of fluid, a springactingon the opposite side of said member, valvemeans for varying pressure of iiuid on -saidoneside, a valve controlling communication between. said valve means and said one sideofsaid-member and operative to closesaid communication. and connect said one side to atmosphere, power' means having a lostmotion connection with said control member for adjustingthe control member, and means positively connected-to said power means and operative by the power means during the lost motion movement thereof to-effect the operation of 'said valve means.

38: In ay fluid pressure operated load compensating;A brake equipment the combination withfa brakepipeland a iiuid pressure vresponsive loady measuring mechanism, of valve means for controllinga communication through which fluid under pressure may be'supplied from said brake pineto-saidl load" measuringl mechanism and a communicationforventingsaid fluid under pressure: from s'aidzmechanism, andV movable abutment" means having differential areas subject to the1pre'ssure'of .fluid in said brake pipe, saidmovablefabutment' meansbeing operated-by an increase thefpressureiof'fluid'in thebrake pipe from -a chosen low degree of pressure to'a certain higher degree of pressure to actuate saidvalve means to close the first named communication and open the second named communication and operative upon a decrease in the pressure of fluid in the brake pipe from said certain higher degree of pressure to said chosen low degree of pressure to close said second communication and open said first communication.`

39. In a fluid pressure operated load coinpensating brake equipment, the combination With a brake pipe and a uid pressure responsive load measuring mechanism, of a cut-off valve device comprising a casing having a first passage open to said brake pipe and a second passage open to said load measuring mechanism, and a third passage open to atmosphere, a normally open supply valve for controlling communication between said first passage and said second passage, a normally closed exhaust valve for controlling `communication between said second passage and said third passage, a piston member for operating said supply and exhaust valves comprising a large piston subject on one side to the pressure of fiuid in said first passage and on the other side to the pressure of fluid in said second passage and comprising a small piston rigidly attached to said large piston and subject on the adjacent side to the pressure of fluid in said second passage and `on the other side to the atmospheric pressure in said third passage, and resilient means urging said piston member toward a position for opening said supply valve and closing said exhaust valve, said piston inember being operative upon an increase in 'fluid pressure in said brake pipe passage from a certain degree to a chosen degree to close said supply valve and open said exhaust valve and operative upon a decrease in fluid pressure in said brake pipe passage from said chosen degree to said certain loWer degree to open said supply valve and close said exhaust valve.

40. In a fluid pressure operated load cornpensating brake equipment, the combination with a brake pipe and a fluid pressure responw sive load measuring mechanism, of a cut-off' valve device comprising a casing havingy a first passage connected to said brake pipe, a second passage directly connected to said load measur ing mechanism and a third passage open to atn mosphere, valve means having one position in which said second passage is connected to said first passage and cut oi from said third passage and operable to another position in which said second passage is cut off from said first passage and connected to said third passage, and mov able abutment means responsive to an increase in fluid pressure in said first passage to a chosen degree to actuate said valve means to its said one position, said movable abutment means being responsive thereafter to a reduction in fluid pressure in said first passage to a predetermined lower degree to actuate said valve means to its said other position.

second passage is cut ofi from said first passage and connected to said third passage, said valve means comprising a movable abutment having a given area responsive to the pressure of fluid in said first passage When said valve means is in said one position and a second movable abutment positively connected to the rst movable abutment having a different area responsive to the pressure of iiuid in said rst passage when said means is in said other position, and resilientmeans opposing the force exerted by fluid pressure on either of said movable abutments.

42. In a fluid pressure operated load compensating brake equipment, the combination with a brake pipe and a fluid pressure responsive load measuring mechanism, of a cut-off valve device comprising a casing having a first passage connected to said brake pipe, a second passage connected to said load measuring mechanism and a third passage open to atmosphere, valve means having one position in which said second passage connected directly to said rst passage andl operable to another position in which said second passage is cut off from said first passage and connected to said third passage, movable abutment means for operating said valve means, said abutment means having differential areas biased by the pressure of fiuid in said one passage in a direction for movingsaid valve means to said other position, and resilient means biasing said abutment means in a direction for moving said valve means to said one position, the effective area of the abutment means acted upon by the fluid at the pressure in said first passage being greater after said abutment means has actuated said valve means to its said other position.

43. In a vehicle fluid pressure brake equipment, a brake cylinder device, a brake pipe normally charged with fluid under pressure, a brake controlling valve device operative in response to a reduction in brake pipe pressure to supply fluid under pressure to the brake cylinder device to effect an application of the brakes and operative in response to a subsequent increase in brake pipe pressure to release fiuid under pressure from the brake cylinder device, a, brake cylinder pressure retaining valve device for controlling the release of fluid under pressure from the brake cylinder device by way of said brake controlling valve device and for retaining fluid at a chosen pressure in the brake cylinder, valve means operative in response to the pressure of uid supplied to said brake cylinder to supply fluid under pressure to establish a force to oppose the action of said brake cylinder device and thereby control the braking force exerted by the brake cylinder device, said valve means being operative in response to a reduction in the pressure of fluid in the brake cylinder to reduce the pressure of uid establishing the force acting in opposition to the action of the brake cylinder device, and said valve means being operative to terminate the reduction in the pressure of iluid establishing the force opposing the action of the brake cylinder device.

44. In a vehicle variable load uid pressure brake equipment, a brake cylinder device comprising a casing and a piston operatively mounted therein for controlling the brakes, said piston and casing defining one chamber into which fluid under pressure may be supplied to cause said piston to operate to effect an application of the brakes and from which uid under pressure is released to effect a relief of the brakes, said piston and casing also defining another chamber into which: ud; under; pressure; may bre; supplied; to. act4 onsaid; piston.: to; oppose. the fomezof.; uid.

under pressure: in'w said. one.. chamber? amrY actingf 3Z brakecylinder.: pressureA retainingY valve.. device operativefto retain a; chosenpressure insaid; one chamber, said.-,Va-1vemeansi being conditionable accordingy to. different- Weights ofthe: load;A car.- riedl'by theNehicleto operate in res-ponselto the retainedfbrake' cylinder pressure. to -retaincorre.; spondingly different pressures insaid other. chamber.

ARTHURA J. BENT.

REFERENCES.- CITED The followingy references are of record'in the le of this' patent:

UNITED STATES PATENTS.

Name DateV Borde et a1 Sept; 2'6, 1939v Number' 

